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158 The Southwestern Nalurali.st vol. 30, no. I Funds for this project were provided by U.S. Fish and Wildlife Contract 14.16.0008.1061A2. The project was administered by the Uiah Cooperative Fishery Research Unit, which is jointly spon. sored by the Iltah Divisor of Wildlife Resources, Iltah Stan, University. and U.S. Fish and Wild- life Service.-RICHARD PINIENTAI., Ross V. BULKLEY AND IIARULD M. '1'vus, Utah Cooperative Fishery Research Unit UMC 52, Utah State Univ., Logan UT 84322 (present address, HMT, U.S. Fish and Wildlife Service, 447 East Main St., Vernal, UT 84978). A SOUTHWARD MOVEMENT OF THE PAINTED LADY BUTTERFLY IN WYOMING.- The painted lady butterfly. Cynthia cardui (l,.), is a well known migratory butterfly. But unlike the monarch, Danaus plexippus (L.)., which regularly migrates north and south in North America (Urquhard, F.A., The monarch butterfly. Univ. of Toronto Press, 361p., 1960), its movements are irregular. In some years huge numbers are seen flying in fixed directions, but in other years this buuerfly is rare or absent (Williams, C.B., The migration of butterflies. Oliver and Boyd, Eclin- burgh, 473p.1930; Insect migration. Collins, London, 235p., 1958, Baker, R.R., Animal migration. Hodder and Stoughton, London 1978). Numerous northward movements, usually in spring and early summer, have been reported in North America (Tilden, T.W., J. Res. Lepid. 1:43.49 1962), but there are only two published accounts of it southward movement in the fall (Emmet, T.C. and R.A. Wobus, J. Lepid. Soc. 20:1234.1234, 1966; Shapiro, A.M., Pan-Pacific Entomol. 56:319.322, 1980). In this paper we describe a southward movement of painted ladies through Yellowstone National Park, Wyoming, in September 1979. One of us (D.F.O.) has watched migratory flights of butterflies in many parts of the world and knows that a migration can be detected only when large numbers of individual butterflies are involved. During the first days of September, 1979, the most abundant butterfly that we observed in Yellowstone National Park was the painted lady, Cynthia carduii (L.). In the early afternoon of 6 Sept., over an open area on the slopes of Mt. Washburn (site I in Fig. I) we observed painted ladies streaming south against a fresh southward wind in warm, sunny weather. They flew pur- posefully and rarely deviated from their course or settled on the rather sparse vegetation. Attempts to count them were futile but led to conservative estimates of thousands per hour over a front of at least 100 in in width. We were obviously observing a large-scale southward migration that roust have been going on for more than one day because of the large numbers seen on 6 Sept. On 8 Sept., we saw only one painted lady passing the same site despite warm sunny weather, ideal for migration. Subsequent to the spectacular movement past Mt. Washburn, we observed additional southward flights in other parts of the Park. During the first three weeks of September painted ladies were commonly seen flying south through the Lower Geyser Basin of Yellowstone Park, although never zo concenu:ued as on Mt. Washburn. Nuutbers varied greatly from day to day, giving the impression of waves of migrants passing through. We concentrated our observations at places such as passes or pemtinsulas, where migrants would tend to be concentrated. For example, at Pumice Point (site 3 in Fig. 1), a small peninsula in Yellowstone Lake, painted ladies set out over the lake at it rate of one a minute between 1150 and 1215 hours on 8 Sept. Several perched on the rocks for a few minutes before attempting the flight across the water against a light southerly wind. On 9 Sept., in the early afternoon, we repeatedly saw individuals set out across the lake only to be blown back by the fresh southwest wind. A few were eventually successful, especially later in the afternoon when the wind speed diminished. By I I Sept. large numbers of painted ladies were moving south through the slope below Soli- tary Geyser in the Lower Geyser Basin of Yellowstone (site 4 in Fig. 1). The rate of I/min. on I I Sept. over a 50 m, front diminished to less than one butterfly per 15 minutes on 12 Sept. On the theory that the large number of butterflies observed on Mt. Washburn on 6 Sept. was again encountered in part at Pumice Point on 8 Sept., we decided to travel south through the only pass toward the south entrance of the Park and attempt to catch up with that particular wave of migrants. This we apparently succeeded in doing on 9 Sept. about 5 km. south of the south entrance to the Park where we observed 6 butterflies passing south within 8 minutes. In this area and for about 10 km further south toward Jackson Lake, painted ladies were common, feeding from flowers or flying south. If these butterflies were indeed part of the movement witnessed cross- ing Mt. Washburn on 6 Sept., they had travelled at least 60 km in 2.3 days. By the third week of Sept. few painted ladies were seen in or around Yellowstone National Park. March 1985 Notes 159 FIG. 1.-Yellowstone National Park, Wyoming, showing the location of five sites where south- ward movements of painted ladies were seen. Land over 1300 in elevation is shaded. In 1980, from Aug. 17 to Sept. 19, one of us (R.G.W.) repeatedly visited the same areas of Yel- lowstone but saw not a single painted lady. During the course of research work in Yellowstone Park during the summers of both 1981 and 1982 a few painted ladies were seen but there was no evidence of any southward migration. In 1983 however, painted ladies were seen in late August and were judged to be about one-half as abundant as in 1979. Almost all butterflies observed in 1983 were either feeding or flying in it generally southward direction. These five consecutive years of observation of this butterfly agree with previous reports (Williams, 1930, 1958; Tilden, 1962) that abundance and movement of the painted lady are irregular and unpredictable. Painted ladies are known to breed in winter in northern Mexico and southern California. Possi- bly the butterflies we saw moving south through Wyoming eventually reached Mexico. The assumption that the summer-autumn Yellowstone migration in 1979 was part of a more general movement is supported by Shapiro's (1980) report of large numbers of Cynthia (=Vanessa) carduii moving south in California during this same period. Shapiro also reported that the reproduction by this species failed in the autumn of 1979. If this failure was also general, it would explain the apparent absence of painted ladies from Yellowstone Park in 1980 and the slow buildup observed in the years since. Our data, plus the known difficulty of detecting insect migration when density is very low, are consistent with the suggestion by Shapiro (1980) that migration may be a normal seasonal aspect of Cynthia carduii. Because this species undergoes such marked fluctuations in density, the migration simply goes undetected in years of scarcity.-D. F. OWEN, Oxford Polytech- nic, Dept. of Biol., Headington, Oxford OX30BP, England and R. G. WIEGEaT, Dept. of Zool., Univ. of Georgia, Athens, GA 30602 USA. MELANISTIC PRONGHORN FAWNS ON THE DESERT EXPERIMENTAL RANGE, UTAH,-This report documents three occurrences of mefanistic pronghorn (Antilocapra ameri- cana) fawns born on the Desert Experimental Range in western Utah. Neither personal communi- cations with experienced observers of pronghorns nor the literature has yielded mention of other occurrences of ntelanistic pronghorn fawns.